Our Best Bet for Colonizing Space May Be Printing Humans on Other Planets

Assuming human deep space travel turns out to be not just incredibly dangerous, but perhaps “crazy idiotic" and "laughable," as Harvard biologist Gary Ruvkun put it, the tenacious dream of an interstellar civilization forces some out-of-the box thinking. What if, instead of rocketing humans to other planets, we made an exact copy on site?

Adam Steltzner, the lead engineer on the NASA JPL's Curiosity rover mission, believes that to send humans to distant planets, we may need to do one of two things: look for ways to game space-time—traveling through wormholes and whatnot—or rethink the fundamental idea of "ourselves."

"Our best bet for space exploration could be printing humans, organically, on another planet," said Steltzner on stage at Smithsonian Magazine’s Future Is Now conference in Washington, DC this month.

Many of science’s brightest minds think that the only way to guarantee the long-term survival of the human race is to colonize other planets—problem is, we have no clue how to safely travel to Mars, let alone further into our cosmic neighborhood.​ By sending instructions on how to print ourselves to far-flung locales, we could skip the trip.

The "printing" idea starts out by encoding human genetic information in bacteria so that our DNA can hitch a ride to another planet. Scientists recently discovered that microbes can survive the trip from Earth to Mars, so the theory is, why not bring some genetic code along next time? Then once the DNA-toting microbes arrive on the new planet, the building blocks of life are reassembled as a human being.

"Once you propose terraforming, you might as well propose sending bacteria with human sequences. That's not that crazy."​

"Maybe we will colonize other worlds not with astronauts in space suits, but with bacteria," said Steltzner at the event. "Those considerations seem beautiful, fantastic."

Ruvkun told me that it is possible to encode segments of human DNA in bacteria and have it survive the trip to other planets. “Like using bacteria like computer memory,” he said. 'It's sort of like an iPod that you send to another planet. And the bacteria can store information very densely."

It’s an extension of the idea to engineer bacteria to send into space to terraform Mars. These microbial pioneers would stimulate the evolution of a new biosphere, the theory goes, providing oxygen and food and the environment that Earthling settlers would need to live on the red planet.

"Once you propose terraforming, you might as well propose sending bacteria with human sequences," said Ruvkun. "That's not that crazy."

Printing human organs is on the frontier, but printing a human—or growing one from DNA—is still only theoretical.

What is potentially crazy, however, is the plan to reassemble the sequence on the other side. At this point, that’s beyond what’s we’re capable of. "We don't have any ability to sort of reassemble a human from DNA,” said Ruvkun.

But it’s also not entirely outside the realm of possibility. As genetic engineering, cloning, and bioprinting technology advances, it’s providing a lot of food for the imagination. If you put a 100th of a human genome into bacteria, Ruvkun said, you'd have to assemble 100 human segments, Ruvkun said. That seems doable.

"We're only 50 years into the DNA era," he said. "Five thousands years in, we'll probably think of that as a piece of cake."

But engineering bacteria in a university lab is one thing. If you’re trying to reconstruct an entire human on distant planet with no intelligent life, who’s even doing the reassembling? And this is where the idea gets really wacky.

If you want to roll with the terraforming scenario a bit further, you can imagine the human-encoded bacteria reassembles naturally, through organic processes, to eventually evolve into descendant organisms—sort of restarting the human population.

“Maybe that process has happened before,” Steltzner told me over the phone this weekend. “Maybe that's how we got here.”

That line of thinking opens up a host of questions about how life came to be in the first place. Did someone else terraform Earth to create us? Do we share a microbial ancestor with Mars? If we custom-make life to survive on other planets, are we ‘playing god?’ Is ‘life’ more than a reconstructed genome? But let’s snap that Pandora’s Box shut for now and move onto scenario B: artificially constructing our biological building blocks after they hitchhike through deep space.

One idea floated by Steltzner is that we beam the human genome into the universe through radio waves—like we're already doing to try to communicate with intelligent life—and see if anyone receives the transmission and can figure out how to interpret it.

Maybe we send along detailed instructions with the signal, or encode a user’s manual of sorts in the DNA-carrying bacteria. Maybe we even send a robot to another planet, wait a thousand years to make sure we trust the machine, and then "beam the information about a human being and tell it to genetically construct the human," Steltzner mused.

"The idea of 3D printing is, something's created out of matter at the location, just with the information. And that's kind of what we're talking about here,” Steltzner said. "That kind of feels like a very fancy 3D printing to me.”

If we believe it's possible to print a Martian organism on Earth, could it work the other way around?

It sounds far-fetched, but it’s an area of biotech geneticists are currently exploring. Being able to store and transmit genetic code the same as any other kind of data is the principle behind the “life printing” gadget being developed by biologist Craig Venter, the US biologist that’s famous for helping map the human genome and creating the first synthetic life.

Venter is developing a “digital biological converter” device that can transport a digital DNA file, at the speed of light, and recreate the original lifeform in the new location from that data. He calls it biological teleportation, but it’s more like a cosmic fax.

So if we believe it's possible to print a Martian organism on Earth, could it work the other way around? At this point, Venter’s experiment is only tackling life-printing at the individual gene level, but single-celled organisms like bacteria are next in line. “More complex creatures,” the New York Times reported, “earthly or Martian, will probably never be possible.”

Probably not. But in Ruvkun’s view, this method of “human” space exploration is worth thinking about, if for no other reason than it’s the least unlikely of all the unlikely schemes to colonize the cosmos.

If we're going to talk about interplanetary settlements anyway, we might as well discuss the strategies that aren't definitely scientifically impossible, he reasoned. We know which laws of physics are standing in the way of transporting people lightyears through the universe, but there aren't obvious laws of nature preventing us from sending DNA-encoded organisms to propagate the species on other planets.

"This is completely speculative," Steltzner said at the end of our interview. "But it doesn't require you moving faster than the speed of light, and it doesn’t require infinite amounts of energy.”